Proclaim

From ConTeXt wiki

In Plain-TeX there is the command \proclaim which is very handy when writing mathematics and stating theorems, lemmas, definitions and so on. Unfortunately it doesn't allow one to number automatically these statements in order to refer to them through cross referencing, and somehow it has disappeared from ConTeXt.

If one wishes to number all these ‘proclaimations’, regardless of type and in the order in which they appear, here is a solution which works very well in ConTeXt Mark II. (For a solution with Mark IV see below.)

\setuppapersize[A5]

%% defining an enumeration environment replacing Plain-TeX's \proclaim
\defineenumeration[proclaim]
	[text=,
	style=slanted,
	title=yes,
	titleleft=,
	titleright=,
	location=serried,
	width=fit,
	right={. }]

%% this can be changed according to one's wishes
\setupnumber[proclaim][way=bysection, numbersection=yes] 

%% end definition \proclaim

\starttext
\title{On proclamations}
\blank

When no section is declared (yet), the numbers have no prefix, as follows:

\startproclaim[def:test]{Definition}
This is a definition.
\stopproclaim

\startproclaim{Lemma}
This is a lemma.
\stopproclaim

\section{Here is a section}

When there is a declared section, the numbers have the section number as a 
prefix number, like so:

\startproclaim{Lemma}
Here is another lemma.
\stopproclaim

\startproclaim[thm:result]{Theorem}
This is our main theorem.
\stopproclaim

\section{Here is another section}

\startproclaim[lem:resultB]{Lemma}
Here is an elementary lemma.
\stopproclaim

\startproclaim{Corollary}
This is a corollary.
\stopproclaim

Note that we can refer to our results in the following way: according to 
\in{Definition}[def:test] we see that \in{Theorem}[thm:result] is an 
easy consequence of \in{Lemma}[lem:resultB].

\stoptext


In Mark IV there is another solution which consists in defining first a certain ‘enumeration’ (in the example below for Remarks) and then use the counter created for this enumeration in other enumerations such as lemmas, theorems, etc.

% mode=mkiv

\setuppapersize[A5]

\defineenumeration[remark]
	[text=Remark,
	location=serried,
	width=fit,
	right={.~}]
\setupenumerations[remark]
	[prefix=yes,
        % or prefixsegments=chapter:section
	prefixsegments=section] 
\setupnumber[remark][way=bysection]

\defineenumeration[theorem]
	[text=Theorem,
	location=serried,
	width=fit,
	counter=remark, % only use counter of remark
	style=slanted,
	right={.~}]
\setupenumerations[theorem]
	[prefix=yes,
	prefixsegments=section]

\starttext

\title{First and only title of the article}

This file has been typeset 
on \currentdate{} 
at \currenttime, 
with 
\doifmodeelse{mkiv}
	{mkiv, 
	LuaTeX version \the\luatexversion,
	LuaTeX revision \luatexrevision,
	(LuaTeX date stamp \luatexdatestamp),
	using the command: \par
	\type{context basic-test.tex}\par}
	{mkii, 
	using the command: \par
	\type{texexec basic-test.tex}\par}
	ConTeXt version \contextversion.
Here we don't have any section.

\startremark
This is a silly remark.
\stopremark

\starttheorem
This is a deep theorem.
\stoptheorem

\startremark
This is a silly remark.
\stopremark

\starttheorem
This is a deep theorem.
\stoptheorem

\section{This is a section}

Here we do have a section.

\startremark
This is a silly remark.
\stopremark

\starttheorem
This is a deep theorem.
\stoptheorem

\startremark[rem:silly]
This is a silly remark.
\stopremark

\starttheorem[thm:deep]
This is a deep theorem.
\stoptheorem

As mentioned in \in{Remark}[rem:silly], the result of 
\in{Theorem}[thm:deep] is trivial.

\stoptext